Stock-Based Compensation - Schedule of Assumptions Used in Determining the Estimated the Fair Value of Stock Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assumptions used in determining the estimated fair value of stock options
Risk-free interest rate (as a percent)	2.17%	1.08%	0.83%
Expected option life, Executive	6 years 10 months 17 days	6 years 3 months 26 days	5 years 5 months 9 days
Expected option life, Non-Executive	6 years 2 months 5 days	4 years 9 months 18 days	4 years 5 months 12 days
Volatility (as a percent)	37.52%	40.12%	45.76%
Weighted-average fair value per option granted	$ 17.91	$ 11.07	$ 10.24